In-situ polymerization of PMMA inside decellularized dermis using UV photopolymerization

Preparation of hybrid meniscal constructs using hydrogels and acellular matrices

To search for a suitable meniscus repair material, acellular hybrid scaffolds consisting of in situ cross-linkable 3-D interpenetrating network structures were obtained by decellularization of the meniscus tissues followed by integration of the gel system. Decellularization efficiency was confirmed using a DNA quantification assay (82% decrease in DNA content) and histological stainings. In the second part of the study, the gelatin molecule was functionalized by adding methacrylic anhydride and the degree of functionalization was found to be 75% by (Proton-Nuclear Magnetic Resonance) ¹H-NMR. Using this, a series of hybrid constructs named GelMA-Hybrid (G-Hybrid), GELMA/PEGDMA-Hybrid (PG-Hybrid), and GelMA/PEGDMA/HAMA-Hybrid (PGH-Hybrid) were prepared by cross-linking with UVA. Changes in the chemical structure were determined with Fourier Transform Infrared Spectrophotometer (FTIR). Water uptake capacities of cross-linked hybrid structures were measured in swelling studies, and it was found that hybrid scaffolds showed similar swelling properties compared to native counterparts. By compressive mechanical tests, enhanced mechanical properties were revealed in cross-linked scaffolds with PGH-Hybrid having the highest cross-link density. Protein denaturation and decomposition transition temperatures were improved by adding hydrogels to acellular scaffolds according to thermal gravimetric analyses (TGA). Cross-linked acellular scaffolds have exhibited a behavior close to native tissues with below 25% mass loss in phosphate buffer saline (PBS) and enzymatic solution. Cell viability was examined through Alamar Blue on the first day and cell viability in hybrid constructs was found to be above 80% while it was closer to the control group on the 7^th day. It was concluded that the developed biomaterials could be used in meniscus tissue engineering with their tunable physicochemical and mechanical properties.

Hierarchically Porous Microspheres by Thiol-ene Photopolymerization of High Internal Phase Emulsions-in-Water Colloidal Systems

A facile method for the preparation of hierarchically porous spherical particles using high internal phase water-in-oil-in-water (w/o/w) double emulsions via the photopolymerization of the water-in-oil high internal phase emulsion (w/o HIPE) was developed. Visible-light photopolymerization was used for the synthesis of microspherical particles. The HIP emulsion had an internal phase volume of 80% and an oil phase containing either thiol pentaerythritol tetrakis(3-mercaptopropionate) (PETMP) or trimethylolpropane tris(3-mercaptopropionate) (TMPTMP) and acrylate trimethylolpropane triacrylate (TMPTA). This enabled the preparation of microspheres with an open porous morphology, on both the surface and within the microsphere, with high yields in a batch manner. The effect of the thiol-to-acrylate ratio on the microsphere diameter, pore and window diameter, and degradation was investigated. It is shown that thiol has a minor effect on the microsphere and pore diameter, while the acrylate ratio affects the degradation speed, which decreases with increasing acrylate content. The possibility of free thiol group functionalization was demonstrated by a reaction with allylamine, while the microsphere adsorption capabilities were tested by the adsorption of methylene blue.